With the development of electronic technology, various types of electronic products have been developed. In particular, as computers are used widely, the distribution rate of computer peripheral devices has also been increasing. The computer peripheral devices refer to devices which improve usability of computers, and include such image forming apparatuses as a printer, a scanner, a copier, an MFP, etc.
The image forming apparatuses use an ink or a toner to print an image on a paper. An ink or a toner is used every time an image forming job is performed and used up if it is used for more than a predetermined time. In this case, a unit which stores the ink or the toner should be replaced. As such, a part or an element which is replaced in the process of using an image forming apparatus is referred to as a consumable unit or a replaceable unit. For convenience of explanation, it will be referred to as a consumable unit in this specification.
The consumable unit includes not only a unit which should be replaced when it is used up, such as an ink or a toner, but also a unit which should be replaced after a predetermined period of time since its properties change as time goes by and thus, high printing quality cannot be expected. That is, the consumable unit may also include such parts as a color developer and an intermediate transfer belt. Such consumable units should be replaced regularly at an appropriate replacement time.
The replacement time may be determined using a use condition index. The user condition index represents the degree of use of an image forming apparatus, and may be the number of papers which are printed and output from an image forming apparatus, the number of dots forming an image, etc. An image forming apparatus may count the number of papers or dots to determine the replacement time of each consumable unit.
Recently, in order to allow a user to determine the replacement time of each unit accurately, a CRUM unit may be mounted or dismounted in each consumable unit.
If a consumable unit is mounted on an image forming apparatus, a CRUM unit and the image forming apparatus are able to communicate with each other through each terminal. The CRUM unit includes a power terminal to receive power provided from the image forming apparatus. Accordingly, the power provided from the image forming apparatus is transmitted to the power terminal, and the CRUM unit may operate by receiving the power from the power terminal.
However, considering the structural features, the presence of a power terminal to provide power may increase the number of interfaces of the CRUM unit. The increasing number of terminals or interfaces also increases the size of the CRUM unit, influencing the costs of the CRUM unit.
In addition, as the power is supplied even during a pause in operation, when data is not received or transmitted through the power terminal, the power consumption of the image forming apparatus increases. In order to overcome the above disadvantages, it has been suggested to remove the power terminal and use only two terminals which combine data with a clock. However, unlike the case where data and clock are separately embodied, an interface circuit of a main board needs to be constructed using an analog method, and therefore, there are drawbacks of complicated circuit map and limitation of speed, or the like.
It is an object of the present invention to address the abovementioned disadvantages.